Passive smoking has been shown to be a risk factor for respiratory diseases in children. Some authors reported reduced lung function of children exposed to passive smoking. The purpose of the study was to assess the prevalence of exposure to passive smoking and its relation to respiratory health of Kaunas children. In 1998-2000 a cross-sectional survey was conducted in 20 kindergartens of Kaunas. Survey participants were 594 children (356 boys and 238 girls) aged 6-7 years. Children's parents filled out a questionnaire of the Swiss Study on Childhood Allergy and Respiratory Symptoms with Respect to Air Pollution designed on the basis of International Study of Asthma and Allergy in Childhood. Exposure to passive smoking was determined by an answer "everyday" or "sometimes" to the question "How often is your child in surrounding where someone smokes?". The parameters of respiratory function (FVC, FEV1, FEV1/FVC, FEF25, FEF50, FEF75, PEF) were measured with Pony Graphics 3.5. Response rate was 58.6% to 69.2% depending on a kindergarten. More than two fifth of children were exposed to passive smoking at home. Cough that lasted for at least four weeks during the past year was experienced by 24.5% and 16.9% of children with and without exposure to passive smoking (p<0.05). Wheezing in the past was found in 43% and 27% of children in groups compared (p<0.05). There was a significant difference in prevalence of sneezing or a runny/blocked nose when a child did not have a cold among children with and without exposure to passive smoking (46.6% and 36.6%, respectively, p<0.05). FEF25, FEF50, FEF75 and PEF of exposed girls were significantly lower than that of girls not exposed to passive smoking. Multiple regression analysis that included variables such as passive smoking, family history of allergy, smoked mother during pregnancy, gas stove and pets in child's room showed that FEF25 and FEF50 in girls were related to passive smoking. Our data show that more than two fifth of children are exposed to passive smoking which is associated with increased prevalence of chronic cough, wheezing, running nose and sneezing without cold. Passive smoking is also related to decreased lung function, especially for small airway flows.